NM_000218.3:c.940G>C

Variant names:

• chr11-2583453-G-C
• rs120074184
• NM_000218.3:c.940G>C
• KCNQ1 p.Gly314Arg

GermlineCancer (beta)

Variant summary

Our verdict is Likely pathogenic.

+8 Likely Pathogenic

-7

-6

-1

0

+5

+6

+9

+10

BenignB

Likely BenignLB

UncertainVUS

Likely PathogenicLP

PathogenicP

The variant received 8 classification points (ACGS-UK Somatic Oncogenicity v2025). O1_ModerateO3_ModerateO5_SupportingO6_SupportingO7_SupportingO8_Supporting

The NM_000218.3(KCNQ1):c.940G>C (p.Gly314Arg) variant causes a missense change involving the alteration of a conserved nucleotide. The gene KCNQ1 is a tumor suppressor gene (CancerMine: 11 TSG, 2 oncogene citations). The gene KCNQ1 is a known oncogene (CancerMine: 11 TSG, 2 oncogene citations). The variant is absent from the gnomAD population database at sites with sufficient sequencing coverage. In-silico predictor (REVEL) classifies this variant as likely damaging/oncogenic. Splicing prediction tools (SpliceAI) predict no significant impact on normal splicing. The affected nucleotide is highly conserved across species (PhyloP 100-way vertebrate score: 9.36). Variant has been reported in ClinVar as Pathogenic/Likely Pathogenic (★★). ClinVar reports functional evidence for this variant: "SCV000738018: Several alterations impacting this codon have been identified in multiple patients with LQTS, and one (p.G314S, c.940G>A) has been reported to co-segregate with disease in multiple families and has demonstrated significantly reduced IKs current density in heterologous expression studies (Russell MW et al. Hum. Mol. Genet., 1996 Sep;5:1319-24" and additional evidence is available in ClinVar. A different missense at the same amino acid position has been reported as Pathogenic/Likely Pathogenic in ClinVar: p.G314D: Pathogenic (ClinVar VariationId 53138, 2 stars) Other variants at the same amino acid position have been reported in ClinVar (not pathogenic): p.G314A: not_provided (ClinVar VariationId 67126); p.G314C: not_provided (ClinVar VariationId 53137); p.G314= (synonymous): Likely_benign (ClinVar VariationId 4614417, 1 star); p.G314= (synonymous): Likely_benign (ClinVar VariationId 4614419, 1 star); p.G314= (synonymous): Likely_benign (ClinVar VariationId 4614420, 1 star) This exact variant is curated in the UniProt human variants database as Pathogenic, associated with Long qt syndrome 1 (lqt1).

• Frequency: Genomes: not found (cov: 33)
• Consequence: KCNQ1 NM_000218.3 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:2 O:1
• Conservation: PhyloP100: 9.36
• Publications: 33 publications found

Genes affected

KCNQ1 (HGNC:6294): (potassium voltage-gated channel subfamily Q member 1) This gene encodes a voltage-gated potassium channel required for repolarization phase of the cardiac action potential. This protein can form heteromultimers with two other potassium channel proteins, KCNE1 and KCNE3. Mutations in this gene are associated with hereditary long QT syndrome 1 (also known as Romano-Ward syndrome), Jervell and Lange-Nielsen syndrome, and familial atrial fibrillation. This gene exhibits tissue-specific imprinting, with preferential expression from the maternal allele in some tissues, and biallelic expression in others. This gene is located in a region of chromosome 11 amongst other imprinted genes that are associated with Beckwith-Wiedemann syndrome (BWS), and itself has been shown to be disrupted by chromosomal rearrangements in patients with BWS. Alternatively spliced transcript variants have been found for this gene. [provided by RefSeq, Aug 2011]

KCNQ1 Gene-Disease associations (from GenCC):

• long QT syndrome

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• Jervell and Lange-Nielsen syndrome

  Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
• Jervell and Lange-Nielsen syndrome 1

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: G2P, Labcorp Genetics (formerly Invitae)
• long QT syndrome 1

  Inheritance: AR, AD Classification: DEFINITIVE, STRONG Submitted by: G2P, Labcorp Genetics (formerly Invitae)
• atrial fibrillation, familial, 3

  Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)
• short QT syndrome

  Inheritance: AD Classification: STRONG, SUPPORTIVE Submitted by: ClinGen, Orphanet
• short QT syndrome type 2

  Inheritance: AD Classification: STRONG Submitted by: G2P, Labcorp Genetics (formerly Invitae)
• familial atrial fibrillation

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• Jervell and Lange-Nielsen syndrome

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• familial hypertrophic cardiomyopathy

  Inheritance: AD Classification: NO_KNOWN Submitted by: G2P
• hypertrophic cardiomyopathy

  Inheritance: AD Classification: NO_KNOWN Submitted by: ClinGen

Classification according to ACGS-UK Somatic Oncogenicity v2025

Specifications for KCNQ1 are available in the ClinGen Criteria Specification Registry and recommended for reference when assigning criteria.

Classification was made for transcript:

Our verdict: Likely_pathogenic. The variant received 8 points.

Apply	Criterion Code & Title / Strength	Strength	Rationale / Clinical Context
	O1Established oncogenic variant		TSG gene: ClinVar germline P/LP ★★+ — Moderate (O1); O1 contributing sources (2.0 pts): ClinVar germline P/LP in TSG (★★)
	O3Absent or very rare in population		Absent or extremely rare in gnomAD (AC ≤ 2) — O3 moderate; GnomAD: AF = absent, AC = 0 — absent/extremely rare (O3 moderate [+2])
	O5Same location/impact as known oncogenic		Different AA at same residue with oncogenic evidence (or germline P/LP in TSG), or same AA change SCI Tier II Potential — Supporting (O5); ClinVar same-AA oncogenic/T1: false | ClinVar same-AA SCI tier: — | CGI same-AA oncogenic: false | TSG: true | ClinVar same-AA germline P/LP: false | CIViC LOF: false | ClinVar diff-AA oncogenic: false | ClinVar diff-AA germline P/LP: true
	O6Computational evidence supports deleterious effect		Computational evidence supports a deleterious/oncogenic effect; Missense variant — primary computational scorer supports an oncogenic/deleterious effect
	O7Mutational hotspot or critical domain		Supporting: cancerhotspots.org hit, critical domain, or missense neighbourhood hotspot; No cancerhotspots.org hit at this position; UniProt domain: 0 pathogenic, 0 benign.; ±8 AA neighbourhood: 32 pathogenic, 0 benign (OR vs. background: 325.0); Variant does not impact splicing — splice-hotspot path not applicable
	O8Missense constraint in gene or region		Missense in gene/domain constrained for missense variation where missense is common disease mechanism (O8 supporting); Gene/disease mechanism: missense is a common mechanism of oncogenesis; gnomAD missense Z-score: 0.91 (threshold ≥3.09 for constraint); Domain-level constraint: variant is in a critically constrained functional domain (IS_AT_CRITICAL_DOMAIN)

Variant Effect in Transcripts

Automated classification analysis was done for transcript: NM_000218.3. You can select a different transcript below to see updated classification assignments.

RefSeq Transcripts

Sel.	Gene / Transcript	Tags	HGVSc / HGVSp	Effect	Exon rank	Protein / UniProt
	KCNQ1 NM_000218.3	MANE Select	c.940G>C p.Gly314Arg	missense	Exon 7 of 16	Prot: NP_000209.2
	KCNQ1 NM_001406836.1		c.940G>C p.Gly314Arg	missense	Exon 7 of 15	Prot: NP_001393765.1
	KCNQ1 NM_001406837.1		c.670G>C p.Gly224Arg	missense	Exon 8 of 17	Prot: NP_001393766.1

KCNQ1 NM_000218.3

MANE Select

HGVSc / HGVSpc.940G>Cp.Gly314Arg

Exon rankExon 7 of 16

missense

Prot: NP_000209.2

KCNQ1 NM_001406836.1

HGVSc / HGVSpc.940G>Cp.Gly314Arg

Exon rankExon 7 of 15

missense

Prot: NP_001393765.1

KCNQ1 NM_001406837.1

HGVSc / HGVSpc.670G>Cp.Gly224Arg

Exon rankExon 8 of 17

missense

Prot: NP_001393766.1

Ensembl Transcripts

Sel.	Gene / Transcript	Tags	HGVSc / HGVSp	Effect	Exon rank	Protein / UniProt
	KCNQ1 ENST00000155840.12	TSL:1MANE Select	c.940G>C p.Gly314Arg	missense	Exon 7 of 16	Prot: ENSP00000155840.2 UniProt:
	KCNQ1 ENST00000335475.6	TSL:1	c.559G>C p.Gly187Arg	missense	Exon 7 of 16	Prot: ENSP00000334497.5 UniProt:
	KCNQ1 ENST00000910997.1		c.937G>C p.Gly313Arg	missense	Exon 7 of 16	Prot: ENSP00000581056.1 UniProt:

KCNQ1 ENST00000155840.12

TSL:1MANE Select

HGVSc / HGVSpc.940G>Cp.Gly314Arg

Exon rankExon 7 of 16

missense

Prot: ENSP00000155840.2UniProt: P51787-1

KCNQ1 ENST00000335475.6

TSL:1

HGVSc / HGVSpc.559G>Cp.Gly187Arg

Exon rankExon 7 of 16

missense

Prot: ENSP00000334497.5UniProt: P51787-2

KCNQ1 ENST00000910997.1

HGVSc / HGVSpc.937G>Cp.Gly313Arg

Exon rankExon 7 of 16

missense

Prot: ENSP00000581056.1UniProt: A0ACI8SIJ2

Frequencies

Allele frequencies (AF), counts (AC/AN), homozygotes and coverage

Common (AF > 0.05 / Hom > 5)

Rare (AF ≤ 0.0001 / Hom ≤ 1)

Source / population	AF	AC	Hom	AN	Coverage
Global population databases 3 sources Large-scale international reference populations
GnomAD3 genomes	AF:	AC:	Hom:	AN:	Cov:33
GnomAD4 exome	AF:	AC:	Hom:	AN:	Cov:31
GnomAD4 genome	AF:	AC:	Hom:	AN:	Cov:33

Showing 3 sources

ClinVar

ClinVar submissions

Significance: Pathogenic/Likely pathogenic

Revision: criteria provided, multiple submitters, no conflicts

Pathogenic	VUS	Benign	Condition
1	-	-	Cardiovascular phenotype (1)
1	-	-	Long QT syndrome (1)
-	-	-	Congenital long QT syndrome (1)

Computational Scores

Algorithm	Calibrated pred.	Score	Prediction
AlphaGenome AVI	Pathogenic	30
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.59	D
BayesDel_noAF	Pathogenic	0.60
CADD	Pathogenic	31
CardioboostArm	Pathogenic	1.0
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.99	D
Eigen	Pathogenic	0.89
Eigen_PC	Pathogenic	0.74
FATHMM_MKL	Uncertain	0.86	D
FuncVEP CTI	Pathogenic	1.0
GPN-Star LLR	N/A	-12
GPN-Star score	N/A	12
LIST_S2	Uncertain	0.97	D
M_CAP	Pathogenic	0.96	D
MetaRNN	Pathogenic	1.0	D
MetaSVM	Pathogenic	0.89	D
Mutation Taster	N/A	0/100	disease causing (ClinVar)
MutationAssessor	Pathogenic	4.1	H
PhyloP100	Pathogenic	9.4
popEVE	Benign	-4.2
PrimateAI	Pathogenic	0.87	D
PROVEAN	Pathogenic	-7.7	D
REVEL	Pathogenic	0.97
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0010	D
Varity_R	N/A	0.96
VESM-3B	Benign	-16

Showing 29 of 29 scores

Splicing Scores

Algorithm	Calibrated pred.	Score	Prediction
Pangolin (max)	Benign	0.0
SpliceAI score (max)	Benign	0.0	Details are displayed if max score is > 0.2

Showing 2 of 2 scores

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

MaxEntScan Visualizer can be used to analyze the impact of this mutation on the neighboring sequence.

MaveDB functional evidence

MaveDB is a public repository of laboratory assays that test the effect of thousands of variants at once — treat this as supporting research data and interpret it with great caution; it is not a clinical classification.

2 no calibration

2 assays found for this variant.

No calibration: 2 assays (score only).

None of these data are clinically calibrated — they are not validated, so interpret them with great caution.

Protein level

Normalized currents of 62 KCNQ1 missense SNVs in the homozygous state.

Proactive functional classification of all possible missense single-nucleotide variants in KCNQ4

• Gene: KCNQ1
• Assay type: Direct protein function
• Mechanism: Gain or loss of function
• Model system: Other (Cricetulus griseus)
• Score: -0.0121 · p.Gly314Arg (assay numbering)

No calibration data

This score is at approximately the 16th percentile of all variants tested in this assay.

This score has not been calibrated against ACMG evidence — shown for context only, not as clinical evidence.

Protein level

Normalized currents of 62 KCNQ1 missense SNVs in the homozygous state

Proactive functional classification of all possible missense single-nucleotide variants in KCNQ4

• Gene: KCNQ1
• Assay type: Direct protein function
• Mechanism: Gain or loss of function
• Model system: Other (Cricetulus griseus)
• Score: -0.0121 · p.Gly314Arg (assay numbering)

No calibration data

This score is at approximately the 16th percentile of all variants tested in this assay.

This score has not been calibrated against ACMG evidence — shown for context only, not as clinical evidence.

Other links and lift over

dbSNP: rs120074184;

hg19: chr11-2604683;

ACMG debug oncogenicity

ACGS debug oncogenicity

ACMG debug germline

Submit to ClinVar